`riscv_gap` (GAPuino) platform docs: upload commands (`load`, `reqloop`, `ioloop`, `start`, `wait`) left as `@TODO`

In platforms/riscv_gap_extra.rst, the "Running modes" section documents the internal upload commands used to control a running process on GAPuino/GAP8 boards, but every command in the list is a literal placeholder instead of an explanation:

* ``load``, @TODO
* ``reqloop``, @TODO
* ``ioloop``, @TODO
* ``start``, @TODO
* ``wait``, @TODO

(lines 51–55)

These commands are directly user-facing - the same page tells readers they can configure them via board_upload.commands in platformio.ini (default: load reqloop ioloop start wait), and later shows a working example that uses only load start for "Run from RAM (without any bridge interaction)". So users are expected to mix and match these commands to choose a boot/run behavior, but the docs never explain what each one actually does, making it hard to safely deviate from the copy-pasted default.

Suggested fix: replace each @TODO with a short description of what the command does during the GAP8 upload/boot sequence (e.g. whether load transfers the binary, reqloop/ioloop relate to the JTAG bridge request/IO loop, start begins execution, wait blocks until completion). I don't have access to GreenWaves' internal tooling to confirm the exact semantics, so this may need input from a GreenWaves/GAP8 maintainer — happy to help draft the wording once the behavior is confirmed.

Reference:

• File: platforms/riscv_gap_extra.rst, lines 51–55 (command list), line 60 (board_upload.commands default)

Start with the "Running modes" section in platforms/riscv_gap_extra.rst at lines 51–55, then compare the board_upload.commands default at line 60 and the load start example. Confirm the GAP8 upload/boot semantics of load, reqloop, ioloop, start, and wait with a GreenWaves or GAP8 maintainer, and replace each @TODO with an accurate short description.